The present invention relates to control systems for indirect heat exchange. More particularly, the present invention relates to a control system providing proportional bypass to control the characteristics of an indirect heat exchanger over a wide range of heat exchange setpoints.
Indirect heat exchangers are known and are used widely for adding and removing heat to and from a heat carrying medium, usually a liquid such as water, glycol or oil. And, many different forms of control systems for indirect heat exchangers are also known.
Examples of prior approaches are found in the following documents which were considered during preparation of the application leading to this patent: U.S. Pat. No. 4,367,785 to Allen; U.S. Pat. No. 4,095,644 to Huff; U.S. Pat. No. 2,254,917 to E. Schroder; and, French Pat. No. 905,590 to Landis & Gyr S.A.
A hitherto unsolved problem relating to heat exchange control related to the need for precise setpoint temperature regulation at a predetermined setpoint within a wide temperature range.